Molded body

Abstract

The present invention provides a molded article containing γ-alumina that exhibits high dispersibility when supporting a load and that resists aggregation of the load even under hydrothermal conditions. [Solution] The material contains γ-alumina and silica, with a silica content in the range of 1.0% to 15.0% by mass in terms of SiO2, and the spectrum measured by a transmission Fourier transform infrared absorption spectrometer shows a value of 3725 cm⁻¹. -1 ~3740cm -1 A molded body is used in which the absorbance of the spectral peak within the wavenumber range is in the range of 0.200 to 0.500.

Description

[Technical Field]

[0001] The present invention relates to a molded article containing γ-alumina. [Background technology]

[0002] γ-alumina, a type of activated alumina, has a large specific surface area and possesses solid acid and solid basic properties, making it widely used as an adsorbent, catalyst, or catalyst support. For example, its characteristic of possessing solid acid properties allows it to be used as a solid acid catalyst in isomerization reactions and dehydration / hydration reactions. Furthermore, its large specific surface area makes it suitable for use as a catalyst support for dispersing catalytically active metals, and it is widely used as a support in catalysts for hydrogenation reactions, dehydrogenation reactions, and exhaust gas treatment, for example.

[0003] γ-alumina is known to readily transform into boehmite under hydrothermal conditions. When such a transformation occurs, the characteristic features of γ-alumina, such as its specific surface area, solid acidity, and solid base properties, are spoiled. In particular, when γ-alumina is used as a support, there is a problem in that the supported components dispersed on the support aggregate due to the structural changes associated with the phase transition of γ-alumina. Since catalytic and adsorption reactions occur on the surface of the supported components, if the supported components aggregate, the surface area is reduced, leading to a decrease in performance. To solve these problems, various studies have been conducted to improve the stability of γ-alumina under hydrothermal conditions.

[0004] For example, Patent Document 1 discloses a method for suppressing the phase transition from γ-alumina to boehmite under a hydrothermal environment by adding phosphorus components and organic polymer acids to a pseudo-boehmite alumina hydrogel. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2007-302558 [Overview of the project] [Problems that the invention aims to solve]

[0006] The present invention aims to provide a molded article containing γ-alumina that exhibits high dispersibility when supporting a supported component and that is less prone to aggregation of the supported component even under hydrothermal conditions. [Means for solving the problem]

[0007] It contains γ-alumina and silica, with a silica content ranging from 1.0% to 15.0% by mass in terms of SiO2, and the spectrum measured by a transmission Fourier transform infrared absorption spectrometer shows an absorption of 3725 cm⁻¹. -1 ~3740cm -1 The aforementioned problems can be solved by using a molded body in which the absorbance of the spectral peak in the wavenumber range is in the range of 0.200 to 0.500. [Effects of the Invention]

[0008] According to one aspect of the present invention, it is possible to provide a molded article containing γ-alumina that exhibits high dispersibility when supporting a supported component and in which the supported component is less likely to aggregate even in a hydrothermal environment. [Modes for carrying out the invention]

[0009] Hereinafter, a molded article according to an embodiment of the present invention (hereinafter also referred to as "the molded article according to this embodiment") will be described in detail. In this specification, when a numerical range is indicated by "~", that numerical range includes both an upper and lower limit. For example, "1~2" means "1 or more and 2 or less".

[0010] [Molded body according to this embodiment] The molded article according to this embodiment contains γ-alumina and silica, with a silica content in the range of 1.0% to 15.0% by mass in terms of SiO2, and the spectrum measured by a transmission Fourier transform infrared absorption spectrometer is 3725 cm⁻¹. -1~3740cm -1 The absorbance of the spectral peaks within this wavenumber range is in the range of 0.200 to 0.500.

[0011] The molded article according to this embodiment must contain γ-alumina. γ-alumina has a large specific surface area and provides high dispersibility when dispersing supported components. Whether or not a molded article contains γ-alumina can be determined using X-ray diffraction measurement, as described later.

[0012] The molded article according to this embodiment preferably has a γ-alumina content in the range of 15.0% to 99.0% by mass, and more preferably in the range of 90.0% to 99.0% by mass. When the γ-alumina content is within the above range, the solid acid content and specific surface area of ​​the molded article according to this embodiment tend to be higher. A high solid acid content makes it suitable for use as a catalyst or catalyst support in reactions where the solid acid acts as the active site. Furthermore, a high specific surface area makes it easier to disperse the supported component. Catalysts and adsorbents with high dispersibility of the supported component tend to have high catalytic activity and high adsorbent removal rates, and are therefore suitable for use as supports for these. The γ-alumina content is obtained by converting the Al content obtained using the high-frequency inductively coupled plasma (ICP) emission spectrometry method described later into an Al2O3 content. In addition, if diffraction peaks originating from Al compounds other than γ-alumina cannot be confirmed in X-ray diffraction measurement, this Al content is considered to be the γ-alumina content.

[0013] The molded article according to this embodiment must contain silica. The silica exists in particulate form in the molded article according to this embodiment, and its physical properties such as specific surface area, water absorption capacity, and crush strength, as well as the spectrum measured by the transmission Fourier transform infrared absorption spectroscopy device described later, are 3725 cm⁻¹. -1 ~3740cm -1It affects the absorbance of spectral peaks in the wavenumber range. Furthermore, some of it may form composite oxides with alumina. As the amount of silica-alumina composite oxide increases, the amount of solid acid increases, making it suitable for use as a catalyst or catalyst support in reactions where solid acid acts as the active site. Whether or not a molded article contains silica can be determined using the ICP emission spectrometry method described later.

[0014] The molded article according to this embodiment must have a silica content in the range of 1.0 mass% to 15.0 mass, in terms of SiO2. Preferably, the silica content is 2.0 mass% or more, and more preferably 4.0 mass% or more. As the silica content increases, the specific surface area and solid acid content tend to increase as well, making it suitable for use as a catalyst or catalyst support in reactions where solid acid acts as an active site. The silica content may be 10.0 mass% or less, or 8.0 mass% or less. The silica content is calculated by converting the Si content obtained using the ICP emission spectrometry method described later into an SiO2 content.

[0015] The molded body according to this embodiment exhibits a spectrum of 3725 cm⁻¹ measured by a transmission Fourier transform infrared absorption spectroscopy device. -1 ~3740cm -1 The absorbance of the spectral peaks in the wavenumber range must be in the range of 0.200 to 0.500. There are two types of spectral peaks that appear in this wavenumber range: those originating from weakly basic OH groups and those originating from isolated silanol groups. The absorbance of the former increases or decreases depending on the surface state of γ-alumina, and the absorbance of the latter increases or decreases depending on the surface state of silica. In the molded article according to this embodiment, if the absorbance of the composite peak that appears when these two spectral peaks overlap falls within the aforementioned range, the dispersibility when supporting the supported component will be high, and the supported component will not aggregate easily even in a hydrothermal environment. In order to achieve both of these, it is important to adjust the absorbance of the spectral peaks that appear in the aforementioned wavenumber range to the range of 0.200 to 0.500.

[0016] The molded body according to this embodiment preferably has a solid acid amount of 360 μmol / g or more, more preferably 400 μmol / g or more, and particularly preferably 500 μmol / g or more. When the solid acid amount is high, it can be suitably used as a catalyst for a reaction in which the solid acid serves as an active site or a carrier for the catalyst. The solid acid amount may be 1000 μmol / g or less, may be 900 μmol / g or less, or may be 800 μmol / g or less. The solid acid amount is a value calculated from the amount of ammonia desorbed obtained by the ammonia temperature-programmed desorption method described later.

[0017] The molded body according to this embodiment preferably has a solid base amount of 10 μmol / g or more, more preferably 15 μmol / g or more, and particularly preferably 20 μmol / g or more. When the solid base amount is high, it can be suitably used as a catalyst for a reaction in which the solid base serves as an active site or a carrier for the catalyst. The solid base amount may be 100 μmol / g or less, may be 90 μmol / g or less, or may be 80 μmol / g or less. The solid base amount is a value calculated from the amount of carbon dioxide desorbed obtained by the carbon dioxide temperature-programmed desorption method described later.

[0018] The molded body according to this embodiment has a specific surface area of preferably 300 m 2 / g or more, more preferably 320 m 2 / g or more, and particularly preferably 340 m 2 / g or more. When the absorbance is within the above range and the specific surface area is large, the supported components are less likely to aggregate even in a hydrothermal environment. The specific surface area may be 800 m 2 / g or less, may be 700 m 2 / g or less, or may be 600 m 2 / g or less. The specific surface area is a value calculated by the BET one-point method using the nitrogen adsorption method described later.

[0019] The molded article according to this embodiment preferably has a water absorption capacity of 0.7 mL / g or more, and more preferably 0.8 mL / g or more. Water absorption capacity represents the volume of water that can be absorbed into the molded article. More specifically, it represents the total volume of pores of a size that can absorb water. A larger water absorption capacity allows for more efficient loading of the supported component when using the impregnation method. The water absorption capacity may be 2.0 mL / g or less, 1.8 mL / g or less, or 1.6 mL / g or less. The water absorption capacity is a value measured by a water absorption test described later.

[0020] The molded article according to this embodiment preferably has a crush strength of 5 N / mm or more, and more preferably 7 N / mm or more. A higher crush strength makes it less likely for cracking or powdering to occur when filling the reactor. The crush strength may be 50 N / mm or less, 40 N / mm or less, or 30 N / mm or less. The crush strength is the value measured by the crush strength measurement test described later.

[0021] The molded article according to this embodiment is a molded article, not a powder. Its shape is preferably spherical, columnar, or a columnar-like shape (for example, macaroni-shaped, trefoil-shaped, quadruple-shaped, or spoke-shaped). If it is spherical, its average diameter refers to the diameter and is preferably in the range of 1 mm or more and 10 mm or less. If it is columnar or a columnar-like shape, its average diameter refers to the major axis of the cross-section and is preferably in the range of 1 mm or more and 10 mm or less. Furthermore, its average length is preferably 2 mm or more and 30 mm or less.

[0022] The molded body according to this embodiment is suitable as a carrier for catalysts and adsorbents, and is particularly suitable as a carrier for supporting precious metals. Furthermore, even without supporting a supporting component, the molded body according to this embodiment can be used as a catalyst for isomerization reactions, dehydration and hydration reactions, etc., by utilizing the chemical properties of γ-alumina. Because the molded body according to this embodiment has water-heat resistance, it is particularly suitable for use as a catalyst in reactions in environments where water is present.

[0023] The method for manufacturing a molded article according to this embodiment will be described in detail as an example, including a gelation step in which a silica component is added to an aluminum-containing basic aqueous solution and then mixed with an aluminum-containing acidic aqueous solution to obtain a silica-containing pseudoboehmite gel; a molding step in which the silica-containing pseudoboehmite gel is molded to obtain a silica-containing pseudoboehmite molded article; and a firing step in which the silica-containing pseudoboehmite molded article is fired to obtain a molded article containing silica and γ-alumina. However, the method for manufacturing a molded article according to this embodiment is not limited to this method.

[0024] This manufacturing method requires a gel preparation step in which a silica component is added to an aluminum-containing basic aqueous solution, and then mixed with an aluminum-containing acidic aqueous solution to obtain a silica-containing pseudoboehmite gel. In this gelation step, it is also necessary to adjust the amount of silica component added so that the silica content of the final molded article containing silica and γ-alumina is in the range of 1.0% to 15.0% by mass. By adding the silica component to the aluminum-containing basic aqueous solution, silica is highly dispersed in the silica-containing pseudoboehmite gel, making it easier for a complex oxide of silica and alumina to form in the final molded article containing silica and γ-alumina, and also making it easier for the amount of solid acid to increase. Furthermore, by preparing the pseudoboehmite gel by mixing an aqueous solution containing aluminum, the specific surface area of ​​the final molded article containing silica and γ-alumina tends to increase. The silica-containing pseudoboehmite gel obtained in this step may be a wet gel or a dry gel.

[0025] In this gelation step, an aluminum-containing basic aqueous solution can be obtained by conventionally known methods, such as dissolving an aluminum-containing compound in a basic aqueous solution or dissolving an alkali salt such as sodium aluminate in water. At this time, the pH of the aluminum-containing basic aqueous solution is preferably 10 or higher, and more preferably 12 or higher. As a method for adjusting the pH, a conventionally known basic aqueous solution such as ammonia water or sodium hydroxide aqueous solution can be added. Furthermore, the aluminum-containing basic aqueous solution may contain a chelating agent such as sodium gluconate to stabilize the dissolved aluminum ions. Moreover, the concentration of aluminum in the aluminum-containing basic aqueous solution is preferably in the range of 1% by mass or more and 10% by mass or less, in terms of Al2O3.

[0026] In this gelation process, the silica component added to the aluminum-containing basic aqueous solution can be any conventionally known component. For example, silica sol, fumed silica, sodium silicate, etc., can be used. When using silica sol or fumed silica, it is preferable to use silica with a small particle size, specifically silica in the range of 100 nm or less. By using silica with a small particle size, the silica can be highly dispersed in the silica-containing pseudoboehmite gel. Also, the amount of isolated silanol groups tends to increase. When using sodium silicate, it can be added directly to the aluminum-containing basic aqueous solution. In this process, it is preferable to add sodium silicate as the silica component. By adding sodium silicate as the silica component, the amount of isolated silanol groups tends to increase.

[0027] In this gelation step, an aluminum-containing acidic aqueous solution can be obtained by conventionally known methods, such as dissolving an aluminum-containing compound in an acidic aqueous solution, or dissolving aluminum sulfate, aluminum nitrate, etc., in water. At this time, the pH of the aluminum-containing acidic aqueous solution is preferably 5 or less, and more preferably 3 or less. As a method for adjusting the pH, a conventionally known acidic aqueous solution containing hydrochloric acid, nitric acid, sulfuric acid, etc., can be added. Furthermore, the concentration of aluminum in the aluminum-containing acidic aqueous solution is preferably in the range of 0.5% by mass or more and 5% by mass or less, in terms of Al2O3.

[0028] In this gelation process, a silica-containing pseudoboehmite gel is formed by mixing an aluminum-containing basic aqueous solution containing silica with an aluminum-containing acidic aqueous solution. At this time, the temperature of both aqueous solutions is preferably 40°C or higher. If the amount of silica-containing pseudoboehmite gel produced is small, the pH may be adjusted to a range of 6 to 8 using a conventionally known acid or base. Afterward, the pH may be adjusted to a range of 9 to 10 using a conventionally known base, and the mixture may be aged at 40°C or higher for 30 minutes or more.

[0029] The silica-containing pseudoboehmite gel obtained in this gelling process contains salts derived from acids or bases as impurities, so it may be washed with warm water, ammonium sulfate aqueous solution, dilute ammonia water, etc., if necessary. For example, the silica-containing pseudoboehmite gel may be washed with the aforementioned warm water, etc.

[0030] This manufacturing method must include a molding step to obtain a silica-containing pseudoboehmite molded body by molding the silica-containing pseudoboehmite gel. In this molding step, the silica-containing pseudoboehmite gel can be molded into a molded body using conventionally known molding methods such as tableting or extrusion molding. For example, when molding using the extrusion molding method, the silica-containing pseudoboehmite gel can be made into a clay-like state and then extruded into a desired shape using an extrusion molding machine. For example, the silica-containing pseudoboehmite gel can be kneaded into a clay-like state using a kneader or other mixing machine. If the silica-containing pseudoboehmite gel does not become clay-like even after kneading with a mixing machine, it is preferable to adjust the viscosity by adding a solvent or a conventionally known thickener. Furthermore, the silica-containing pseudoboehmite molded body obtained in this molding step can also be dried at a temperature of 300°C or lower.

[0031] This manufacturing method requires a firing step to obtain a molded body containing silica and γ-alumina by firing the silica-containing pseudo-boehmite molded body. In this firing step, the pseudo-boehmite undergoes a phase transition to γ-alumina. The firing temperature should be above the temperature at which the pseudo-boehmite transitions to γ-alumina, preferably in the range of 500°C to 700°C, and more preferably in the range of 525°C to 600°C. If the firing temperature is too high, the γ-alumina may transition to another phase. Also, if the firing temperature is too low, the transition to γ-alumina will not be promoted. The firing time is preferably in the range of 0.5 hours to 48 hours, and more preferably in the range of 1 hour to 24 hours. [Examples]

[0032] The method for manufacturing molded articles according to this embodiment will be described in detail below using examples. However, this embodiment is not limited to these examples.

[0033] [Analysis method] Each of the molded articles obtained in the examples was analyzed by the following method.

[0034] (0)Si content and Al content measurement The formed body was pulverized in a mortar until it became powdery. 3 g of this powder was weighed into a zirconium crucible with a lid having a volume of 30 mL, and heat-treated at 200 °C for 2 hours. Then, it was further fired at 700 °C for 5 minutes. After firing, 2 g of sodium peroxide and 1 g of sodium hydroxide were added to the crucible and melted at 700 °C for 15 minutes. After cooling the crucible to room temperature, sulfuric acid was added to dissolve the melt in the crucible, and it was diluted with pure water so that the volume became 500 mL. Using this as a measurement sample, the Si content rate and the Al content rate were measured using a high-frequency induction plasma (ICP) emission spectroscopic analyzer (manufactured by Shimadzu Corporation, ICPS-8100, analysis software ICPS-8000), and these were converted to the Si content rate and the Al content rate of the formed body. The Si content rate and the Al content rate were taken as values converted to SiO2 and Al2O3, respectively. <0---000148><0---000149><0---000150>(1) Measurement of average diameter and average length <0---000151>Under the following conditions, the average diameter and average length of the formed body were measured. <0---000152>· Number of samples: 40 (random sampling) <0---000153>· Diameter measurement: Using a micrometer <0---000154>· Length measurement: Using a digital caliper <0---000155><0---000156><0---000157>(2) X-ray diffraction measurement <0---000158>Under the following conditions, X-ray diffraction measurement of the formed body was performed to confirm the presence or absence of γ-alumina. <0---000159><0---000160><0---000161><X-ray diffraction measurement> <0---000162>X-ray diffractometer: MineFlex600 (manufactured by Rigaku Corporation) <0---000163>X-ray source: Cu-kα ray <0---000164>Accelerating voltage, current: 40 KV, 15 mA <0---0​​​​​​​​The X-ray diffraction patterns obtained from the above X-ray diffraction measurements were checked for the presence or absence of diffraction peaks attributed to γ-alumina using the integrated powder X-ray analysis software PDXL (manufactured by Rigaku Corporation). If diffraction peaks attributed to γ-alumina were detected, it was determined that the sample contained γ-alumina.

[0038] (3) Water absorption capacity measurement The molded body was pre-treated at 500°C for 1 hour. After pre-treatment, the molded body was transferred to a desiccator containing a desiccant and cooled. It was then removed from the desiccator and weighed out 10 g. A small amount of water was added to this molded body and mixed. This process was repeated until the surface of the molded body became wet and began to stick together, allowing the molded body to absorb water. The mass of the molded body after water absorption was measured, and the water absorption capacity was calculated using the following formula. The density of water was assumed to be 1 g / mL.

[0039] Water absorption capacity [mL / g] = ((Mass of molded body after water absorption [g] - 10 [g]) / Density of water [g / mL]) / 10 [g]

[0040] (4) Measurement of ammonia desorption by heating (NH3-TPD) The amount of solid acid in the molded body was measured under the following conditions.

[0041] <Measurement of solid acid amount> Equipment: Catalytic converter BELCATII (Microtrac-BEL Co., Ltd.) Method: NH3-TPD method Pretreatment: 500°C, 30 minutes (under heat flow) NH3 adsorption: 100°C, 30 minutes Desorption temperature and heating rate: 100°C to 700°C, 10°C / min Sample weight: 0.05g Method for calculating solid acid content: Using the included analysis software (ChemMaster), the amount of NH3 elimination in the NH3 elimination spectrum was integrated in the range of 100°C to 600°C to calculate the amount of solid acid.

[0042] (5) Measurement of carbon dioxide thermal desorption (CO2-TPD) The amount of solid base in the molded product was measured under the following conditions.

[0043] <Solid Base Amount Measurement> Equipment: Catalytic converter BELCATII (Microtrac-BEL Co., Ltd.) Method: CO2-TPD method Pretreatment: 500°C, 30 minutes (under heat flow) CO2 adsorption: 50°C, 30 minutes Desorption temperature and heating rate: 50°C to 700°C, 10°C / min Sample weight: 0.05g Method for calculating solid base amount: Using the included analysis software (ChemMaster), the amount of CO2 elimination in the NH3 elimination spectrum in the range of 100°C to 600°C was integrated to calculate the amount of solid base.

[0044] (6)Specific surface area measurement The specific surface area of ​​the molded body was measured under the following conditions.

[0045] <Specific surface area measurement> • BET specific surface area measuring device: Macsorb HM Model-1220 (manufactured by Mountec Co., Ltd.) • Calculation method: BET1 method • Sample weight: 0.1g Pre-treatment: 500℃ for 1 hour

[0046] (7) Measurement of crush strength The crush strength of the molded body was measured under the following conditions.

[0047] <Measurement of crushing strength> The molded body was pre-treated at 500°C for 1 hour. After pre-treatment, the molded body was transferred to a desiccator containing a desiccant and cooled. Using this molded body as a sample, its length was measured using a crushing strength measuring device (compressor width 20 mm), and then it was compressed and the load at which it was crushed was measured. This measurement was performed for 50 samples, and the crushing strength was calculated using the following formula. The arithmetic mean was used as the measured value.

[0048] Crushing strength (N / mm)=S / L S: Pressurized load (N) L: Length of the measured sample (mm)

[0049] (8) Transmission Fourier transform infrared absorption spectrum measurement Using a transmission Fourier transform infrared absorption spectroscopy analyzer (JASCO Corporation: FT-IR / 6100), the following measurements were taken, corresponding to the weakly basic OH group and the isolated silanol group at 3725 cm⁻¹. -1 ~3740cm -1 The absorbance of spectral peaks within the specified wavelength range was determined.

[0050] 20 mg of crushed molded material is filled into a molded container (inner diameter 20 mmφ) and filled at a rate of 4 tons / cm². 2 It was compressed under pressure and formed into a thin disc shape. This thin disc-shaped molded body was subjected to a vacuum of 1.0 × 10⁻⁶ ―3 Under conditions below Pa, the sample was held at 500°C for 2 hours, then cooled to room temperature and the absorbance was measured. Specifically, a TGS detector was used with a resolution of 4 cm. ―1 The number of cumulative operations was set to 200, and the wavenumber range was 3000 cm. ―1 ~4000cm ―1 Baseline correction was performed.

[0051] (9) Assessment of variance A palladium nitrate solution (Furuya Metal Co., Ltd., palladium concentration 4.63% by mass) was spray-impregnated into a molded body so that the palladium concentration after loading was 0.5% by mass, and then dried at 110°C for 12 hours. The dried molded body was added to 100 times the volume of pure water (60°C) and stirring was continued. Then, 5 times the molar amount of formic acid relative to the loaded palladium was added and held for 60 minutes. After that, the molded body was dehydrated and separated, and washed with pure water at 60°C until the conductivity of the filtrate was 200 μS / cm or less. Then, it was dried at 110°C for 12 hours to prepare a palladium-supported molded body. The palladium particle size of this palladium-supported molded body was measured under the following conditions as a sample.

[0052] <Palladium (Pd) particle size measurement> Equipment: Catalytic converter BELCATII (Microtrac-BEL Co., Ltd.) Method: CO pulse method Pretreatment: 300°C, 1 hour (under hydrogen flow) Sample weight: 0.20g Palladium concentration in the sample: 0.5% by mass

[0053] (10) Water and heat resistance evaluation 100 g of pure water and 5 g of the palladium-supported molded body prepared in (9) above were placed in a 200 mL stainless steel pot-type autoclave and kept at 140°C for 6 hours. After that, the palladium-supported molded body was separated by dehydration and dried at 110°C for 12 hours. The palladium particle size (after hydrothermal treatment) was measured using the same method as in (9) above as a sample. The palladium particle size (before hydrothermal treatment) from (8) above was used as the palladium particle size (before hydrothermal treatment), and the palladium particle growth rate was calculated from the following formula.

[0054] Palladium particle growth rate [%] = Palladium particle diameter (after hydrothermal treatment) / Palladium particle diameter (before hydrothermal treatment) × 100

[0055] Furthermore, X-ray diffraction measurements were performed using the same method as in (2) above. The diffraction peak of the (021) plane of boehmite was identified from the diffraction pattern obtained using the integrated powder X-ray analysis software PDXL (manufactured by Rigaku Corporation), and the crystallite size of the boehmite (021) plane was calculated using its full width at half maximum.

[0056] The raw materials used in the example are as follows:

[0057] [Raw materials] Sodium aluminate aqueous solution: Al2O3 equivalent concentration 22% by mass Sodium gluconate aqueous solution: 25% by mass concentration Sodium silicate aqueous solution: SiO2 equivalent concentration 5% by mass Aluminum sulfate aqueous solution: Al2O3 equivalent concentration 7% by mass Sodium hydroxide aqueous solution: Concentration 4.8% by mass

[0058] [Example 1] A steam-jacketed tank was filled with 4.57 kg of sodium aluminate solution. Next, 0.119 kg of sodium gluconate and 17.52 kg of pure water were added to the sodium aluminate solution while stirring. Furthermore, 0.3 kg of sodium silicate solution was added to prepare an aluminum-containing basic aqueous solution, and then the temperature was adjusted to 60°C.

[0059] Separately from this aluminum-containing basic aqueous solution, an aluminum-containing acidic aqueous solution was prepared by adding 12.32 kg of pure water to 6.84 kg of aluminum sulfate aqueous solution.

[0060] The aluminum-containing acidic aqueous solution was added in its entirety to the aluminum-containing basic aqueous solution, which had been adjusted to 60°C, over a period of 10 minutes. After stirring for 30 minutes while maintaining the temperature at 60°C, sodium hydroxide aqueous solution was added to adjust the pH to 9.5. Subsequently, the mixture was stirred for another 30 minutes while maintaining the temperature at 60°C to prepare a silica-containing pseudoboehmite gel. This silica-containing pseudoboehmite gel was filtered to separate the solid components, then washed with pure water at 60°C, and dried to obtain a silica-containing pseudoboehmite gel.

[0061] The silica-containing pseudo-boehmite gel was kneaded using a dual-arm kneader with a steam jacket to form a clay-like substance. This was then extruded into a cylindrical shape with a diameter of 2.6 mm using an extrusion molding machine to obtain a silica-containing pseudo-boehmite molded body.

[0062] After drying the silica-containing pseudo-boehmite molded body, it was calcined at 550°C for 3 hours in an air atmosphere to prepare a molded body containing γ-alumina and silica. The aforementioned measurements were performed on this molded body containing γ-alumina and silica. The measurement results for (1) to (8) are shown in Table 1. The measurement results for (9) and (10) are shown in Table 2.

[0063] [Example 2] A steam-jacketed tank was filled with 4.48 kg of sodium aluminate solution. Next, 0.116 kg of sodium gluconate and 17.4 kg of pure water were added to the sodium aluminate solution while stirring. Furthermore, 0.9 kg of sodium silicate solution was added to prepare an aluminum-containing basic aqueous solution, and then the temperature was adjusted to 60°C.

[0064] Separately from this aluminum-containing basic aqueous solution, an aluminum-containing acidic aqueous solution was prepared by adding 12.06 kg of pure water to 6.71 kg of aluminum sulfate aqueous solution.

[0065] In the subsequent steps, a molded article containing γ-alumina and silica was prepared using the same method as in Example 1. The aforementioned measurements were performed on this molded article containing γ-alumina and silica. The measurement results for (1) to (8) are shown in Table 1. The measurement results for (9) and (10) are shown in Table 2.

[0066] [Example 3] A steam-jacketed tank was filled with 4.39 kg of sodium aluminate solution. Next, 0.114 kg of sodium gluconate and 17.27 kg of pure water were added to the sodium aluminate solution while stirring. Furthermore, 1.5 kg of sodium silicate solution was added to prepare an aluminum-containing basic aqueous solution, and then the temperature was adjusted to 60°C.

[0067] Separately from this basic aqueous solution, an aluminum-containing acidic aqueous solution was prepared by adding 11.82 kg of pure water to 6.22 kg of aluminum sulfate aqueous solution.

[0068] In the subsequent steps, a molded article containing γ-alumina and silica was prepared using the same method as in Example 1. The aforementioned measurements were performed on this molded article containing γ-alumina and silica. The measurement results for (1) to (8) are shown in Table 1. The measurement results for (9) and (10) are shown in Table 2.

[0069] [Example 4] A steam-jacketed tank was filled with 4.16 kg of sodium aluminate solution. Next, 0.108 kg of sodium gluconate and 16.98 kg of pure water were added to the sodium aluminate solution while stirring. Furthermore, 3 kg of sodium silicate solution was added to prepare an aluminum-containing basic aqueous solution, and the temperature was adjusted to 60°C.

[0070] Separately from this basic aqueous solution, an aluminum-containing acidic aqueous solution was prepared by adding 12.44 kg of pure water to 6.91 kg of aluminum sulfate aqueous solution.

[0071] In the subsequent steps, a molded article containing γ-alumina and silica was prepared using the same method as in Example 1. The aforementioned measurements were performed on this molded article containing γ-alumina and silica. The measurement results for (1) to (8) are shown in Table 1. The measurement results for (9) and (10) are shown in Table 2.

[0072] [Comparative Example 1] A steam-jacketed tank was filled with 4.62 kg of sodium aluminate solution. Next, while stirring the sodium aluminate solution, 0.12 kg of sodium gluconate and 17.58 kg of pure water were added to prepare an aluminum-containing basic aqueous solution. The temperature of this solution was adjusted to 60°C.

[0073] Separately from this aluminum-containing basic aqueous solution, an aluminum-containing acidic aqueous solution was prepared by adding 12.44 kg of pure water to 6.91 kg of aluminum sulfate aqueous solution.

[0074] In the subsequent steps, a molded body containing γ-alumina was prepared using the same method as in Example 1. The aforementioned measurements were performed on this molded body containing γ-alumina. The measurement results for (1) to (8) are shown in Table 1. The measurement results for (9) and (10) are shown in Table 2. The aforementioned measurements were performed. The results are shown in Table 1.

[0075] [Comparative Example 2] A steam-jacketed tank was filled with 3.7 kg of sodium aluminate solution. Next, 0.096 kg of sodium gluconate and 16.39 kg of pure water were added to the sodium aluminate solution while stirring. Furthermore, 6 kg of sodium silicate solution was added to prepare an aluminum-containing basic aqueous solution, and the temperature was adjusted to 60°C.

[0076] Separately from this aluminum-containing basic aqueous solution, an aluminum-containing acidic aqueous solution was prepared by adding 9.95 kg of pure water to 5.53 kg of aluminum sulfate aqueous solution.

[0077] In the subsequent steps, a molded article containing γ-alumina and silica was prepared using the same method as in Example 1. The aforementioned measurements were performed on this molded article containing γ-alumina and silica. The measurement results for (1) to (8) are shown in Table 1. The measurement results for (9) and (10) are shown in Table 2.

[0078] [Table 1]

[0079] [Table 2]

Claims

1. Containing γ-alumina and silica, The silica content is SiO ２ In terms of conversion, it is in the range of 1.0% by mass to 15.0% by mass. In the spectrum measured by a transmission Fourier transform infrared absorption spectroscopy device, 3725 cm⁻¹ -１ ~3740cm -１ The absorbance of the spectral peaks in the wavenumber range is in the range of 0.200 to 0.

500. Molded body.

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